This invention relates to a process for decontamination of caustic solution, used in the boilout section of a mercerizing facility for cellulosic fabrics, whereby thus-decontaminated caustic can be used in a rinsing bath disposed upstream of the point at which the cloth enters the mercerizer.
Cerini has disclosed, in U.S. Pat. No. 1,719,714, purification of caustic soda by osmotic principles.
Steele et al, in U.S. Pat. No. 2,558,064, have described the preparation of parchmentized paper dialysis membranes, particularly adapted for dialysis of sodium hydroxide solutions.
Nitsche, in U.S. Pat. No. 1,980,498, has described several techniques for reutilization of waste lye from mercerization. Concentration of the waste lye by evaporation is among the contemplated alternatives, but is regarded as being economically unfeasible.
Carr et al, U.S. Pat. No. 2,980,501, purify spent mercerization caustic by treatment with chlorine or a hypochlorite.
Hyperfiltration, ultrafiltration or reverse osmosis treatment of various effluents have been proposed, for example, in the following U.S. Pat. Nos. 3,528,901, Wallace et al: 3,537,988, Marcinkowsky et al: 3,778,366, Kraus: 4,156,621, Andrews et al: 4,165,288, Teed et al.
Hermes has recited, in U.S. Pat. No. 4,055,971, use of filters in a closed-cycle apparatus for continuous, waterless dyeing of textile and plastic materials.
In the context of solvent recovery in commercial washing or dry cleaning of clothing, both Victor (U.S. Pat. No. 3,728,074) and Klein et al. (U.S. Pat. No. 3,841,116) have proposed the use of filters or solid bodies of adsorbent materials to remove contaminants from the solvents.
It has been proposed by Lawrence, in U.S. Pat. No. 4,074,969, to recover and reuse liquid ammonia, used for the processing of fabrics. The reference proposes feeding process effluent to a desuperheating vessel, in which the effluent is brought into direct contact with a body of low temperature liquid ammonia. The condensate formed in the desuperheater is recycled to the process.
Gresens et al have proposed, in U.S. Pat. No. 4,231,165, a process for heattreating fabric webs, wherein waste gas from the treatment unit is treated to remove condensible constituents therefrom and, ultimately, recycled to the treatment unit.
Klare, in U.S. Pat. No. 3,889,390, has disclosed a continuous process for reclamation of softening agent, used to treat regenerated cellulose film. Recovery is accomplished by absorption of the softening agent from an exhaust air stream.
It will be apparent that, although a variety of techniques have been put forth for the treatment of waste from mercerizing or other textile-treating installations, none of the presently available techniques employed in treating caustic wastes from a mercerizing installation is entirely satisfactory in view of economic criteria, which favor processes characterized by low loss of materials and heat, and environmental considerations, which favor processes discharging small volumes of relatively harmless effluents.